Imagine, as the world grows more hot and crowded, not having to using more land for farms but returning some of it instead to forest and grassland. Imagine the reductions in soil erosion and water consumption, the decline of greenhouse gas emissions, and a host of other benefits for our planet.

It 's possible. Corn farmers have shown how.

So as we mark Earth Day this April, I want to call attention to an aspect of corn farming that is too often lost in the story of our food systems. I want to celebrate the astounding—and hugely significant—increase in the ability of corn farmers to bring more food to harvest while sustaining the environment over the last 45 years since the first Earth Day.

Do you remember how we grew corn in 1970? I remember the year—and harvest—well. I was leaving home on an Illinois farm headed to college.

In 1970, U.S. corn farmers planted about 67 million acres. They produced 4.1 billion bushels (a bushel is about 56 pounds), for an average yield of about 71 bushels per acre.

Last year, farmers planted about 83 million acres—about 24 percent more. But their production more than tripled to a record 14.2 billion bushels, because they averaged 171 bushels per acre. That's a 140 percent increase in yield from 1970.

Sounds good, right? The numbers get better.

Because farmers today are producing these better yields with fewer inputs than they were years ago.

A few years ago, a Washington, D.C.-based organization called Field to Market (of which Monsanto is a member) compared the use of resources by corn farmers in 2011 with their use of those same resources in 1980. In other words, the organization compared what it took to grow a bushel of corn in each of those years.

In 2011, the organization's study found, farmers used:

• 30 percent less land
• 53 percent less irrigation water
• 44 percent less energy
   

At the same time, farming in 2011 led to 67 percent less soil erosion and 36 percent less greenhouse gas emissions.

How did they pull that off? Through a combination of improved agronomic practices and improved technology.

They learned to plant smarter. They increasingly adopted no-till or conservation tillage farming, which reduces soil erosion, preserves soil moisture and reduces greenhouse gas emissions. And they adopted better technology—including better hybrid seeds and seeds with traits like insect resistance via genetic modification.

In other words, thousands of years of history in growing corn didn 't stop farmers from looking for ways to innovate. And the innovation paid off.

And it not only, I should add, paid off for the farmers. Better harvests help make a balanced meal more accessible for everyone.

Even more importantly, perhaps, all this shows we can  sustainably intensify  agriculture and make the 21st century a bright one.

By 2050, the global population is expected to swell by about 30 percent. And with about three billion people worldwide joining the middle class – and, therefore, eating more diverse and protein-rich diets—global food demand is expected to rise to as much as 70 percent above today's level, according to the United Nations Food and Agriculture Organization. Production in the developing countries, the FAO says, would need to almost double.

Meanwhile, climate change is making it harder to grow crops. We 're rapidly depleting our finite supply of fresh water, and our topsoil is eroding a lot faster than nature can replace it.

Corn points the way forward. It shows we can produce much more food while cutting the resources needed to do it. It offers a model for the kind of sustainable intensification that, if applied to a broad array of crops, would enable humanity to feed itself while shrinking the footprint of agriculture—which is the best thing we could do to preserve and protect our environment.